多路输出反激式开关电源设计要点

多路输出反激式开关电源设计摘要:以UC3844芯片为控制核心，设计并制作了多路输出反激式开关电源。完成了多路输出反激式开关电源系统设计，完成具体模块电路详细设计，包括EMI滤波电路、前级保护和整流桥电路、缓冲吸收电路、高频变压器、UC3844的启动与驱动电路、电流检测和过流保护电路等。合理选择、设计和分配了开关电源各电路参数；设计出电路原理图，根据设计规范制作出PCB，并组装出电源样机，最后对设计的样机进行测试验证。开关电源样机输出电压稳定性较高，输出电压纹波较小，符合设计规范小于80mV的要求；样机整体测试结果表明，电源各项指标均符合要求，输出稳定，性能较好。关键词：开关电源；反激式；UC3844；模块化DesignofMulti-outputFlybackSwitchingPowerSupplyAbstract:Itwasdesignedandproducedasetofmultipleoutputfly-backswitchingpowersupply,usingthechipUC3844asthecontrolcore.Thedesignofthesystemandspecificmodulecircuitswascompleted.ThemodulecircuitsincludeEMIfiltercircuit,levelprotectionandbridgerectifiercircuit,snubbercircuit,highfrequencytransformer,startanddrivecircuitofUC3844,currentsensingandover-currentprotectioncircuit.Theparametersofswitchingpowersupplycircuitwerechose,designedanddistributedreasonably.Accordingtotheschematiccircuitdesignanddesignspecifications,weproducedthePCB,andassembledtheprototypeofpowersupply,alsofinishedthetestinthefinal.Thehigherstabilityoftheoutputvoltageoftheswitchingpowersupplyprototype,theoutputvoltagerippleissmall,meetthedesignspecificationstotherequirementsoflessthan80mV;Theprototypeoftheoveralltestresultsshowthatthepoweroftheindicatorsareinlinewiththerequirements,outputstability,betterperformance.Keywords:switchpowersupply；flyback；UC3844；Modular目录1概述........................................................................................................................11.1课题研究背景与意义.........................................................................................11.2课题设计内容.....................................................................................................12反激式开关电源系统分析............................................................................................12.1反激变换器工作原理分析.................................................................................12.2控制电路分析.....................................................................................................32.3系统整体架构.....................................................................................................53系统设计.........................................................................................................................53.1变压器设计.........................................................................................................53.2控制芯片选择...................................................................................................103.3控制芯片驱动电路及定时电阻电容计算.......................................................123.4缓冲吸收电路...................................................................................................163.5前置保护电路...................................................................................................173.6EMI滤波电路选择与设计................................................................................173.7输入整流滤波电路...........................................................................................183.8反馈电路设计...................................................................................................203.9电流检测和过流保护电路................................................................................213.10软启动电路.....................................................................................................223.11MOS管瞬态抑制保护电路.............................................................................224系统调试......................................................................................................................234.1硬件调试...........................................................................................................234.2空载输出电压波形测量...................................................................................234.3纹波测量与分析...............................................................................................235结束语......................................................................................................................27参考文献..........................................................................................................................28致谢................................................................................................................................29附录..............................................................................................................................30附录1多路输出反激式开关电源原理图.............................................................31附录2多路输出反激式开关电源PCB图............................................................32附录3多路输出反激式开关电源系统元器件清单.............................................33南通农业职业技术学院学生毕业论文1多路输出反激式开关电源设计1概述1.1课题研究背景与意义随着电力电子技术的高速发展，电力电子设备与人们的工作、生活的关系日益密切，而电力电子设备都离不开可靠的电源，其供电一般采用开关电源。开关电源是利用现代电力电子技术，控制开关管开通和关断的时间比率，维持稳定输出电压的一种电源，开关电源一般由脉冲宽度调制（PWM）控制IC和MOSFET构成。在建设资源节约型、环保示范型社会的大背景下，具有高效节能、安全环保、短小轻薄等方面优点的开关电源已经成为本学科一个重要的研究热点。其中反激式开关电源，是开关电源拓扑中最简单的一种。输出变压器同时充当储能电感，整个电源体积小、结构简单，可同时输出多路互相隔离的电压，所以得到广泛应用。本次毕业设计制作的多路输出反激式开关电源是为各种电力电子器件供电。1.2课题设计内容设计多路输出的反激式开关电源，指标如下：(1)输入电压：AC220V±10%(2)输出电压五组：三路+15V(1.0A)、两路+5V（1.0A）(3)输出电压纹波:VPP≤80mV(4)工作频率：100KHz(5)最大占空比：Dmax=0.4